This invention relates to nylon fibers and particularly to their use in carpeting. More specifically, the invention relates to a method of improving the ability of nylon carpeting to resist staining and retaining such resistance even after cleaning.
There is much literature relating to the coating of nylon and other fibers to improve their surface properties and without affecting the physical properties of the nylon itself. The principal problem which has been faced by those working in the field of stain prevention has been retaining the ability to resist staining even after the nylon carpeting has been steam cleaned, a process which might better be called hot water-detergent washing. Surface treatments which are very effective at preventing the nylon from being stained are not usually resistant to the cleaning process to which most carpeting is eventually subjected. The present inventors have addressed this problem and found a method of firmly bonding stain-blocking compounds to the surface of nylon fibers, thus enabling them to resist the hot water washing process.
In, co-pending U.S. patent application Ser. Nos. 7/500,813 and 07/649,501 improved stain-blocking materials have been disclosed. Such materials may be D 30 firmly bonded to nylon by the process to be described below. Similar stain-blocking materials are disclosed in EP 0329,899.
The grafting of various materials to nylon and related polymers has been the subject of much investigation. In U.S. Pat. No. 3,090,664 Cline et al. disclosed a method of grafting an unsaturated organic acid or salt to nylon and other nitrogen containing polymers. The method involved placing the unsaturate acid on the surface of the polymer and then exposing it to ultraviolet light, thereby binding the unsaturated portion of the acid to the carbon adjacent to the nitrogen atom in the polymer chain. This process inherently leaves the acid portion free for further reaction. Photoinitiators were said not to be necessary, but they were preferred.